Data_Sheet_1_Host Gene SEL1L Involved in Endoplasmic Reticulum-Associated Degradation Pathway Could Inhibit Hepatitis B Virus at RNA, DNA, and Protein Levels.docx

Hepatitis B virus (HBV) belongs to the Hepadnaviridae family of enveloped DNA viruses. Recent studies have found that host factors can suppress HBV replication. HBV envelope proteins are reported to be degraded by the endoplasmic reticulum-associated degradation (ERAD) pathway. As a component of the ERAD pathway, suppressor of lin-12-like 1 (SEL1L) was earlier found to be upregulated in the inactive carrier phase of chronic HBV infection relative to that in the immune tolerant phase. However, the role of SEL1L in regulating HBV replication remains largely unknown. In this study, we found the levels of HBV RNA, DNA, and core and envelope proteins to be significantly downregulated by SEL1L overexpression and upregulated by SEL1L silencing in Huh7 cells transiently transfected with an overlength HBV genome. Similar upregulation was observed in HepG2.2.15 cells as well. SEL1L co-localized with HBV surface antigen (HBsAg), which changed its staining pattern. Treatment with an inhibitor of ERAD pathway remarkably increased intracellular S protein. Surprisingly, silencing SEL1L to block the ERAD pathway activated an alternative ER quality control (ERQC)-autophagy pathway, which might account for the increased HBV RNAs and core protein. Together, our results demonstrate that SEL1L is a host restriction factor that exerts anti-HBV effect through ERAD and alternative ERQC-autophagy pathway.

乙型肝炎病毒（HBV）隶属于包膜DNA病毒中的肝腺病毒科。近期研究揭示，宿主因子能够抑制HBV的复制。据报道，HBV包膜蛋白通过内质网相关降解（ERAD）途径被降解。作为ERAD途径的一部分，抑制子lin-12样1（SEL1L）在慢性HBV感染的非活动携带期相对于免疫耐受期被发现在早期表达上调。然而，SEL1L在调节HBV复制中的作用仍鲜为人知。在本研究中，我们发现通过SEL1L过表达显著下调了Huh7细胞中瞬时转染的超长HBV基因组中的HBV RNA、DNA以及核心和包膜蛋白的水平，而通过SEL1L沉默则上调了这些水平。在HepG2.2.15细胞中也观察到了相似的上调现象。SEL1L与HBV表面抗原（HBsAg）共定位，并改变了其染色模式。使用ERAD途径的抑制剂处理显著增加了细胞内S蛋白的含量。令人惊讶的是，通过沉默SEL1L来阻断ERAD途径激活了替代性内质网质量控制（ERQC）-自噬途径，这可能是导致HBV RNAs和核心蛋白增加的原因。综合来看，我们的研究结果证实了SEL1L是一种宿主限制因子，通过ERAD途径和替代性ERQC-自噬途径发挥抗HBV作用。